service: add implementation of count

Adapted commit of FedorSelitsky <[email protected]>
from PR #14

Signed-off-by: Jakub Filak <[email protected]>

Author: fedarsialitski

USAGE.md

@@ -62,6 +62,22 @@ for smith in smith_employees_request.execute():
     print(smith.EmployeeID)
 ```
 
+### Get a count of entities
+
+```python
+# Print a count of all employees
+count = client.entity_sets.Employees.get_entities().count().execute()
+print(count)
+```
+
+### Get a count of entities via navigation property
+
+```python
+# Print a count of all orders associated with Employee 1
+count = client.entity_sets.Employees.get_entity(1).nav('Orders').get_entities().count().execute()
+print(count)
+```
+
 ### Creating entity
 
 You need to use the method set which accepts key value parameters:

pyodata/v2/service.py

@@ -543,6 +543,7 @@ def __init__(self, url, connection, handler, last_segment):
         super(QueryRequest, self).__init__(url, connection, handler)
 
         self._logger = logging.getLogger(LOGGER_NAME)
+        self._count = None
         self._top = None
         self._skip = None
         self._order_by = None
@@ -559,6 +560,11 @@ def custom(self, name, value):
         self._customs[name] = value
         return self
 
+    def count(self):
+        """Sets a flag to return the number of items."""
+        self._count = True
+        return self
+
     def expand(self, expand):
         """Sets the expand expressions."""
         self._expand = expand
@@ -596,9 +602,15 @@ def top(self, top):
         return self
 
     def get_path(self):
+        if self._count:
+            return urljoin(self._last_segment, '/$count')
+
         return self._last_segment
 
     def get_headers(self):
+        if self._count:
+            return {}
+
         return {
             'Accept': 'application/json',
         }
@@ -1064,7 +1076,12 @@ def get_entities_handler(response):
                 raise HttpError('HTTP GET for Entity Set {0} failed with status code {1}'
                                 .format(self._name, response.status_code), response)
 
-            entities = response.json()['d']['results']
+            content = response.json()
+
+            if isinstance(content, int):
+                return content
+
+            entities = content['d']['results']
 
             result = []
             for props in entities:

tests/test_service_v2.py

@@ -1046,3 +1046,81 @@ def test_get_entity_set_query_filter_property_error(service):
     with pytest.raises(KeyError) as e_info:
         assert not request.Foo == 'bar'
     assert e_info.value.args[0] == 'Foo'
+
+
+@responses.activate
+def test_count(service):
+    """Check getting $count"""
+
+    # pylint: disable=redefined-outer-name
+
+    responses.add(
+        responses.GET,
+        "{0}/Employees/$count".format(service.url),
+        json=23,
+        status=200)
+
+    request = service.entity_sets.Employees.get_entities().count()
+
+    assert isinstance(request, pyodata.v2.service.GetEntitySetRequest)
+
+    assert request.execute() == 23
+
+
+@responses.activate
+def test_count_with_skip(service):
+    """Check getting $count with $skip"""
+
+    # pylint: disable=redefined-outer-name
+
+    responses.add(
+        responses.GET,
+        "{0}/Employees/$count?$skip=12".format(service.url),
+        json=11,
+        status=200)
+
+    request = service.entity_sets.Employees.get_entities().skip(12).count()
+
+    assert isinstance(request, pyodata.v2.service.GetEntitySetRequest)
+
+    assert request.execute() == 11
+
+
+@responses.activate
+def test_navigation_count(service):
+    """Check getting $count via navigation property"""
+
+    # pylint: disable=redefined-outer-name
+
+    responses.add(
+        responses.GET,
+        "{0}/Employees(23)/Addresses/$count".format(service.url),
+        json=458,
+        status=200)
+
+    addresses = service.entity_sets.Employees.get_entity(23).nav('Addresses').get_entities()
+    request = addresses.count()
+
+    assert isinstance(request, pyodata.v2.service.GetEntitySetRequest)
+
+    assert request.execute() == 458
+
+
+@responses.activate
+def test_navigation_count_with_filter(service):
+    """Check getting $count via navigation property with $filter"""
+
+    # pylint: disable=redefined-outer-name
+
+    responses.add(
+        responses.GET,
+        "{0}/Employees(23)/Addresses/$count?$filter=City eq 'London'".format(service.url),
+        json=3,
+        status=200)
+
+    addresses = service.entity_sets.Employees.get_entity(23).nav('Addresses').get_entities()
+    request = addresses.filter(addresses.City == 'London').count()
+
+    assert isinstance(request, pyodata.v2.service.GetEntitySetRequest)
+
+    assert request.execute() == 3